Advancing SAM-based tin perovskite solar cells: solvent engineering for post-treatment with ethylenediamine to passivate top perovskite surface

Solvent engineering is herein developed to passivate the top surface of tin perovskite in hole-selective self-assembled monolayer (SAM)-based solar cells by employing chlorobenzene to dissolve ethylenediamine. Chlorobenzene serves to moderate ethylenediamine, which is otherwise aggressive and capable of etching perovskite films. Using the formulated solution, the top surface of tin perovskite is post-treated with ethylenediamine to suppress the formation of Sn vacancy defects, thereby mitigating the non-radiative recombination. This post-treatment leads to a high photovoltage (0.860 V) and a 20.9% augmentation in device efficiency.